Gum loss after root canal

Xrays showed absess (abscess) forming at the bottom of a tooth that had been root canalled when I was young. Last week I underwent surgery to remove the abcess (abscess) and refill the old canal from the bottom. That took about two hours. There was pain and discomfort during the week before having the stitches which I figured was normal. When the stitches were removed the surgeon was surprised to find that the gum had not reattached itself and that there was discoloration of the gum as if the area had not been getting blood. He prescribed a more powerful antibiotic and sent me home for a day to see what would happen. That day I spit up blackened pieces of the gum. Now there is a half inch opening in the gum where the incision was made that exposes three teeth. There are still some blackened spots, especially below the gap. What is going on?

[Jerome Tsang, DDS]

You may want to see an oral surgeon to find out whats going on with the area.  It sounds like it didn't heal properly for some reason and you may need some surgery to replace the injured tissue to get proper healing.  Sorry but I don't know what may have caused it.  I don't do apicoectomy surgeries.